A dry powder insulin formulation delivered by an aerosol inhaler has been in clinical development for use in types 1 and 2 diabetes mellitus (DM) and just recently (1-27-06) received approval from the U.S. Food and Drug Administration (FDA) for the clinical treatment of diabetes. Administration of insulin without the need for subcutaneous (SC) injection is an attractive alternative for patients with diabetes. There are preclinical and clinical data that indicate inhalation of insulin results in a more potent effect on glucose disposal and a lower fasting glucose than is attained with equivalent dosing of SC or intravenous (IV) insulin. The physiological mechanism(s) are unclear, but occur even when matched for pharmacokinetics.